An access barrier, such as a garage door, often includes an operator with a motor that moves the door between opened and closed limit positions. In addition, operators, also referred to as an operating system, may also be coupled with other types of movable access barriers, such as gates, curtains, windows, retractable overhangs and the like. A barrier operating system is employed to control the motor and related functions with respect to the door. Thus, in order to open and close the door, the operator is configured to receive command signals from a wireless portable remote transmitter, a wired or wireless wall station, a keyless entry device or other similar device. Safety devices that are connected to the operator may also be provided for the purpose of detecting an obstruction so that the operator may then take corrective action with the motor to avoid entrapment of the obstruction.
Remote transmitters allow users to open and close garage doors without getting out of their vehicle. In addition, these remote transmitters may also be provided with other features, such as the ability to control multiple doors, lights associated with the operators, and other security features. The remote transmitters and operators may also be provided with encrypted codes that change after every operation cycle so as to make it virtually impossible to “steal” a code and use it at a later time for illegal purposes. The operation cycle of the barrier operator may include opening and closing of the barrier and turning on-and-off a light that is connected to the operator and so on.
Although remote transmitters and similar devices are convenient and generally work well, such remote transmitters tend to become lost, misplaced or broken. Furthermore, the switch mechanism of the remote transmitter typically becomes worn after a period of time and requires replacement. To overcome the deficiencies of the remote transmitters, “hands-free” remote transmitters have been developed in a number of different forms. In general, a “hands-free” remote transmitter does not require a user to initiate physical contact with the transmitter or switch in order to cause some physical action to take place at the barrier operator, such as the movement of the garage door. Prior art hands-free systems comprise a “mobile” transmitter that communicates, via various mobile signals, with the barrier operator that is configured to move an access barrier, such as a garage door, between opened and closed positions. In some hands-free systems, only the mobile transmitter may generate signals that are received and acted upon by the barrier operator. In any event, the mobile transmitter is generally maintained or otherwise carried by a carrying device, such as a vehicle.
During operation, the hands-free mobile transmitter is configured to transmit mobile signals to the barrier operator so as to move the access barrier between open and closed positions depending on the relative position of the carrying device to the barrier operator and various other criteria. Because the operation of the hands-free system requires mobile signals to be generated by the mobile transmitter for a period of time following the activation and deactivation of the carrying device that contains the mobile transmitter, the hands-free system, in one aspect, sends the mobile signals continuously at all times. However, mobile transmitters that continuously transmit mobile signals tend to rapidly consume the capacity of their batteries, thus necessitating the frequent and inconvenient replacement of batteries or recharge thereof. In order to increase the convenience of the system, prior-art systems contemplated the utilization of an activity sensor that comprises a vibration or noise detection sensor, which monitors when the vehicle that carries the mobile transmitter is started or turned off. By monitoring such phenomena, the activity sensor is able to selectively turn the mobile transmitter on and off in an attempt to conserve the battery power used to operate the mobile transmitter.
Another problem with some hands-free systems is that when the hands-free mobile transmitter no longer detects movement of the carrying device, the mobile transmitter stops sending mobile signals. This can be interpreted by the barrier operator that the carrying device has moved sufficiently away from the area, but this may not be the case. As a result, the barrier operator will generate a door close command when in fact such an action is not desired by the user. As a result, although such a hands-free system is effective when the carrying device is approaching and leaving the barrier operator area, unwanted door movements may result.
Therefore, there is a need in the art for a barrier operator system that automatically moves the access barrier depending upon the proximity of a carrying device that is carrying a remote mobile transmitter to the access barrier, wherein the mobile transmitter automatically emits somewhat periodic mobile signals that are received by, or are received and then lost by, a barrier operator, which then moves the access barrier and ignores subsequent transmitter signals for a predetermined period of time. Additionally, there is a need for a mobile transmitter that utilizes an activity sensor, such as an accelerometer, to detect when the carrying device, such as a vehicle, is moving so as to generate mobile signals, and which incorporates warning bits in the mobile signals that indicate when the carrying device is first turning on and when the carrying device is about to turn off.